[[restoring-bootloader-using-live-disk]]
= Restoring the bootloader using the Live disk.

Sometimes, especially after a secondary operating systems has been installed, 
the master boot record gets damaged which then prevents the original Linux system
from booting.

If this happens, it is necessary to reinstall *GRUB2* to recreate the original 
settings. The process not only discovers all installed operating systems, but 
usually adds them to the *GRUB2* configuration files, so they will all become 
bootable by *GRUB2*.

.Before you start

* Get the Fedora Live ISO from link:https://download.fedoraproject.org/pub/fedora/linux/releases/[getfedora.org].

* Prepare a bootable device using the downloaded ISO, either a CD or a USB.

.Procedure

. Boot the Fedora live system from the bootable device you have created.

. Open the terminal.

. Examine the partition layout and identify the `boot` and the `root` partition.

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sudo fdisk -l
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== For Default Installation in LVM.

. Create the mount point for the root partition.
+
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mkdir -p /mnt/root
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If you are using the default Fedora layout, there will be one `/dev/sda1`
partition that holds the `/boot` directory and one `/dev/mapper/fedora-root`
that holds the root file system.

. Mount the root partition on the mount point.
+
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mount /dev/mapper/fedora-root /mnt/root
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. Mount the boot partition in the `boot` directory of the filesystem that you have mounted in the previous step.
+
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mount /dev/sda1 /mnt/root/boot/
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. Mount system processes and devices into the root filesystem in `/mnt/root`.
+
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mount -o bind /dev /mnt/root/dev
mount -o bind /proc /mnt/root/proc
mount -o bind /sys /mnt/root/sys
mount -o bind /run /mnt/root/run
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. If you use EFI boot, you may also want to bind the efivars and the EFI system partition:
+
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mount -o bind /sys/firmware/efi/efivars /mnt/root/sys/firmware/efi/efivars
mount <efi system partition> /mnt/root/boot/efi
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. Change your filesystem into the one mounted under `/mnt/root`.
+
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chroot /mnt/root
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== For Default Installation in BTRFS

. Create the mount point for the root partition.
+
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mkdir -p /mnt/
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If you are using the default Fedora layout, there will be one `/dev/sda1`
partition that holds the `/boot` directory and one `/dev/sda2` that holds the root file system.

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mount /dev/sda2 /mnt
mount /dev/sda1 /mnt/root/boot
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. Change your filesystem into the one mounted under `/mnt/root`.
+
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chroot /mnt/root
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IMPORTANT: Home Partition is mounted automatically under `/mnt/home`

== For Default Installation in LUKS.

. Make sure crypt module in use:
+
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sudo modprobe dm-crypt
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. Find out which drive it was with the following command:
+
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sudo fdisk -l
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You must mount `/dev/sda3 myvolume`

. Use `cryptsetup`, device is accessible under `/dev/mapper/myvolume``
+
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sudo cryptsetup luksOpen /dev/sde3 myvolume
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. Scan for LVM volumes and choose the right volume group name that you are looking for:
+
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sudo vgscan
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. If it is eg. Fedora, activate it
+
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sudo vgchange -ay system
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. Find out root volume
+
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sudo lvs
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. Mount it with the following command:
+
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sudo mount /dev/system/root /mnt/
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. To work in the volume use the following commands
+
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sudo mount --bind /dev /mnt/dev 
sudo mount --bind /dev/pts /mnt/dev/pts
sudo mount --bind /proc /mnt/proc
sudo mount --bind /sys /mnt/sys
sudo chroot /mnt
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IMPORTANT: consider mounting `/boot` also.

== Continue with the follow Procedure.

. Regenerate the *GRUB2* configuration file and reinstall the bootloader 
into the MBR, as described in xref:adding-other-operating-systems-grub2[Adding other operating systems to the *GRUB2* menu].

. Exit this temporary root filesystem.
+
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exit
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. Your bootloader should be now restored. Reboot your computer to boot into your normal system.

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systemctl reboot
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